Therapy methods for a stenosed site caused by plaque, thrombus or the like in coronary arteries can include percutaneous transluminal coronary angioplasty (PTCA) of dilating a blood vessel using a balloon, a method of causing a mesh-shaped or coil-shaped stent to indwell the blood vessel as a support for the blood vessel, and the like. However, these methods are less likely to be applied, when the plaque of the stenosed site becomes calcified and hardened or when the stenosed site develops in a bifurcated portion of the coronary arteries. A method, which can enable treatment, can include atherectomy of cutting a stenosis substance such as the plaque, the thrombus, and the like.
For example, as a device for the atherectomy, JP-T-2003-504090 discloses a device in which diamond particles (abrasive materials) adhere to an outer surface of a rotating body located in a distal end portion of a catheter and the rotating body is rotated inside the coronary arteries so as to cut the stenosis substance. The rotating body of this device includes four bars arrayed in the circumferential direction. These bars are expandable so as to fit a diameter of the blood vessel by bending the bars to protrude radially outward.
When expandable and contractible bars are used as in the device disclosed in JP-T-2003-504090, since an edge of the bars comes into contact with the blood vessel, a normal blood vessel is at considerable risk of being damaged. Furthermore, when a hardened stenosis substance such as calcified plaque is cut, the hardened stenosis substance is caught in a gap between the bars, thereby causing an increasing possibility that the device may be damaged.